Articulated furniture and particularly articulated beds and chairs have gained in popularity over the last decade due in part to the demographic enlargement of the North American and European elderly population and also due to an increase in health and comfort awareness.
Usually articulated furniture includes a stationary frame upon which pivotal or pivotal and slidable back and leg frame members are mounted. Linear drives are provided mounted on the frame that engage the movable leg and back frame members to shift them between their retracted and extended positions. Usually the retracted and extended positions in articulated furniture are fixed in that they are not adjustable except by authorized factory personnel.
These linear drives usually include an electric housing enclosing an electric motor that rotates in opposite directions. The housing also includes a reducing gear box driven by the motor and an elongated rotary output screw that drives a nut carried by a reciprocal tube. The motor or one of the gears in the gear box carries a rotary cam that engages limit switches defining the extremes of motion of the reciprocal output drive tube.
The problem arises because distributors and frequently customers become involved in the assembly of these articulated pieces and while the extent of assembly is usually minor, it sometimes involves connecting one of the linear drives. Since the output drive tube is threaded to the output drive screw, if a customer inadvertently manually rotates the tube in one of the other directions, he changes both the retracted position and the extended position of the articulated furniture frame to which it is connected. This frequently causes jamming of the movable frame members into the stationary frame members locking them up and causing permanent damage to the furniture. In all cases customer rotation of the drive tube improperly positions the head frame or foot frame portion from the desired manufacturer pre-set positions.
Faced with these problems, applicant has provided a simple and economical modification to linear drives to prevent the inadvertent adjustment by distributors or customers.
It is a primary object of the present invention to prevent the inadvertent adjustment of linear drives.